This week, the overall grades of seven Machinery stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Westport Innovations‘s (NASDAQ:WPRT) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Westport Innovations is engaged in the research, development and marketing of high performance, low-emission engine and fuel injection systems that utilize alternative gaseous fuels such as natural gas, propane or hydrogen. For Portfolio Grader’s specific subcategory of Equity, WPRT also gets an F. The stock price has dropped 21.7% over the past month, worse than the 2.1% increase the Nasdaq has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of WPRT stock.

The rating of Woodward (NASDAQ:WWD) declines this week from a C to a D. Woodward designs, manufactures, and services energy control systems and components for aircraft and industrial engines and turbines. The stock also gets an F in Earnings Surprise. Shares of the company are down 4.6% from last month. To get an in-depth look at WWD, get Portfolio Grader’s complete analysis of WWD stock.

Slipping from a C to a D rating, Paccar (NASDAQ:PCAR) takes a hit this week. PACCAR designs, develops, manufactures, and distributes light-, medium-, and heavy-duty trucks, and related aftermarket distribution of parts. For a full analysis of PCAR stock, visit Portfolio Grader.

Graham (AMEX:GHM) earns a D this week, falling from last week’s grade of C. Graham designs and builds vacuum and heat transfer equipment for process industries around the world. The stock gets F’s in Earnings Momentum and Sales Growth. Over the last month, GHM shares are down 0.9%. To get an in-depth look at GHM, get Portfolio Grader’s complete analysis of GHM stock.

Kennametal Inc.‘s (NYSE:KMT) rating weakens this week, dropping to a D versus last week’s C. Kennametal manufactures, purchases, and distributes tools, tooling systems, and solutions to the metalworking, mining, oil, and energy industries. For more information, get Portfolio Grader’s complete analysis of KMT stock.

Timken (NYSE:TKR) earns a D this week, moving down from last week’s grade of C. Timken is a developer, manufacturer, marketer and vendor of products for friction management and power transmission, alloy steels and steel components. The stock also gets an F in Earnings Surprise. Wall Street appears to agree with the stock downgrade, with share prices dropping 8.2% over the past month. For a full analysis of TKR stock, visit Portfolio Grader.

Energy Recovery (NASDAQ:ERII) gets weaker ratings this week as last week’s C drops to a D. Energy Recovery develops and manufactures energy recovery devices utilized in the water desalination industry. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at ERII, get Portfolio Grader’s complete analysis of ERII stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.